The quality of cut lily flowers during its postharvest life is important both for growers and customers. It is determined by two factors: longevity of flowers and a general appearance of the entire cut stem during its vase life. The aim of this work was to evaluate the effects of growth regulators (gibberellic acid and benzyladenine) and the preservative (200 mg·dm^-3 8HQC+2%S) on quality of cut oriental lily ‘Helvetia,’ a white blooming cultivar very popular on the Polish market. After cutting the flowers were treated for 20 h with growth regulators (GA₃ or BA, 500 mg·dm^-3) and then placed into distilled water. Non pulsed flowers were kept in a preservative solution composed of 200 mg·dm-3 8HQC and 2% sucrose. Untreated flowers held in distilled water served as a control. During the senescence of cut lily flowers the soluble protein and free proline contents were determined. As the major problem in the postharvest handling of lilies is leaf yellowing, the effects of postharvest treatments on quality of leaves and their chlorophyll contents were also studied. The preservative increased vase life of cut lily flowers while gibberellic acid improved the quality of leaves. In leaves treated with GA3 the chlorophyll level was 25% higher than in leaves on stems placed into distilled water directly after harvest. The level of soluble protein in petals dropped while free proline accumulated during flower senescence. Flowers treated with GA3 and those placed into 8HQC + 2%S solution showed a delayed protein degradation: the concentrations of soluble proteins after 12 day of vase life was over 3-fold higher than in control flowers. Also the proline accumulation was delayed in flowers on stems placed in the preservative solution, however, no effect of GA3 on the proline level was observed. The soluble protein level correlated with a flower position on the stem being lower in lower flowers as compared to the upper ones.

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